These systems are complex and expensive, as they are based on the retransmission of a microwave signal after a time delay and transposition of the signal by frequency modulation. All these operations involve a considerable number of components.
Furthermore, these systems, which are particularly energy intensive, generally require a mains-type supply. This makes use in the field difficult. If the supply is by a battery, the energy consumption of the active elements limits the autonomy thereof.
Moreover, the presence of active oscillators makes these response systems detectable, which may be prejudicial in certain applications.
In the case of a system on board an aircraft, in which the volume, weight and consumption of the aircraft mains must be minimized, these systems are penalizing.
Finally, said systems require regular maintenance.